Computer users often focus on the speed of computer microprocessors (e.g., megahertz and gigahertz). This speed often comes with a cost—higher power consumption. For one or two home PCs, this extra power may be negligible when compared to the cost of running the many other electrical appliances in a home. But in data center applications, where thousands of microprocessors may be operated, electrical power requirements can be very important.
Power consumption has at least a two-fold effect on costs. Not only must a data center operator pay for electricity to operate its many computers, but the operator must also pay to cool the computers. A pair of microprocessors mounted on a single motherboard can draw hundreds of watts or more of power, which, in turn, produces heat. Multiply that figure by several thousand (or tens of thousands) to account for the many computers in a large data center, and one can readily appreciate the amount of heat that can be generated. The effects of power consumed by the critical load in the data center are often compounded when one incorporates all of the ancillary equipment required to support the critical load.